DESCRIPTION (Applicant's abstract): This proposal outlines a framework for skilled performance that focuses on both relative timing and serial order constraints. Most complex actions produced by humans, such as speech and music, have systematic, information-bearing temporal patterns that are not well-understood. Study of production errors as well as event timing in sequence production has documented constraints on both serial order and temporal characteristics of performance, but the findings are rarely considered simultaneously in theoretical accounts. Experiments are proposed that examine relationships among relative timing and serial order in music performance, a complex production domain which offers considerable flexibility in sequence structure and temporal task demands. With specialized equipment and methodology, we can now precisely measure, analyze, and reproduce event timing and production errors in music performance under natural conditions. Another goal is to determine at what point the cognitive representations for action become independent of the effectors on which they operate. What accounts for differences in motor teaming between effectors (hand I finger movements) and across tasks? A final goal is to address learning: the representational structures and processes that allow us to use past experience to improve future behavior. How do memory structures and processes combine with temporal Constraints to predict a shift from novice to expert sequence production in item selection, range of planning, and effector independence? Experiments address these issues in studies of long-term and short-term practice effects, using a combination of naturalistic and experimental paradigms. Outcomes would have significant impact in their potential for instructional methods and their relevance to other sequence production domains.